Bladder Dose-Volume Parameters Are Associated with Urinary Incontinence After Post-operative Intensity-Modulated Radiation Therapy for Prostate Cancer

Publication date: Available online 19 December 2015
Source:Practical Radiation Oncology
Author(s): Christina H. Son, James Melotek, Chuanhong Liao, Greg Hubert, Charles A. Pelizzari, Scott E. Eggener, Stanley L. Liauw
PurposeUrinary incontinence is a potential side-effect of prostatectomy and intensity modulated radiation therapy (IMRT) for prostate cancer. There are limited data on dosimetric parameters that may predict for poor continence recovery in men who receive post-operative IMRT.Materials and MethodsEighty-seven men with non-metastatic prostate cancer who underwent prostatectomy followed by adjuvant (13%) or salvage (87%) IMRT were identified. The Expanded Prostate Cancer Index composite (EPIC) questionnaire was prospectively collected at baseline, 6 weeks, and 6, 12, 18, 24, 36, and 48 months post-IMRT. Relevant critical structures were contoured and dose-volume metrics collected. The primary endpoint was urinary continence global score. Longitudinal analysis using a generalized estimating equation model was performed.ResultsThere was no statistically significant change in EPIC urinary continence global scores over time as compared to baseline (all p>0.05). In univariate analysis, bladder V70Gy and penile bulb V70Gy were associated with urinary continence (OR 0.82, p<0.05). In a multivariable model that included body mass index, distance between vesicourethral junction and genitourinary diaphragm, time from surgery, use of anti-hypertensive medications, age, diabetes, and bladder V70Gy, only bladder V70Gy (OR 0.82, p=0.03) was associated with outcome. After 2 years, there was a significant difference in global score for those with V70Gy < 42.27 vs. ≥ 42.27 cc (all p<0.05 at 2 and 3 years post-IMRT).ConclusionThere was no significant change in patient-reported urinary continence scores after post-prostatectomy IMRT. Bladder V70Gy was independently associated with a decrease in urinary continence scores. Further evaluation is necessary to optimize quality of life in these men.



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